Submarine



A. R. NEFF Aug. 9, 1932.

SUBMARINE Filed March 18. 1930 5 Sheets-She l A. R. NEFF Aug. 9, 1932.

SUBMARINE Filed March 18. 1930 5 Sheets-Sheet 2 A. R. NEFF SUBMARINEAug. 9, 1932.

Filed March 18, 1950 5 Shams-Shea!- 5 [H van farflner ii.

Aug. 9, 1932. R, FF 1,870 263 SUBMARINE I Filed March 18. 1930 5Sheets-Sheet 4 Invenfar Aug. 9, 1932. A NEFF 1,870,263

SUBMARINE Filed March 18, 1930 5 Shuts-Shoot 5 Patented Aug. 9, 1932ABNEP. RLNEFF, OE LONG BEACH, CALIFQRI'FIA SUBMARINE Application filedMarch 18, 1930. Serial No. 436,705.

This invention relates to submarines, and, in some of its characteristicfeatures, although not necessarily limited wholly thereto, relates tosubmarines of the general type disclosed in the patent issued to John M.Cage, 1,126,- 616, on January 25,1916, and also of the type set out inPatent. No. 1,172,992 granted to me February 22nd, 1916, as the assigneeof Allen Hoar. In the submarine of said Cage patent, propulsion, both onthe surface and submerged, is by means ct combustion engines, dispensingwith the storage battery drive now generally in use for under-water propulsion. It is provided in that patent that air for the combustionengines be stored and carried at high pressure in flasks the enginestaking their air from the interior atmosphere of the submarine, whichinterior atmosphere is supplied from atmospheric air wiile running atthe surface and from the storage while running submerged. The exhaustgases, in the Cage patent, are compressed and expelled overboard by anexhaust compressor operated by the engine. I

In the Hoar patent the propulsion is by combustion engines, both at thesurface and submerged, as in the Cage submarine. In the Hoar system,however, the exhaust gases, after being cooled and somewhat condensed,are compressed and expelled overboard by using the energy of expansionof the stored air.v 7

In the submarine in accordance with my present invention I utilize boththese prior ideas and, among other things, niy present inventionprovides improvements upon those former systems. l e present invention,however, contains other improvements in submarines, as will be set outlater. Generally speaking,-the object or the present invention may bebriefly summarized under the fol lowing heads:

1) To improve the eiiiciency and range of action of submarines which aredriven orclusivelv b 7 combustion en ines: i:

V (:2) To improve the flexibility of operation and control ofsuch asubmarine;

To .providesuch a system of operation that the submarine can eithertravel or lie under water for comparatively long periods withoutbetrayin its presence by any expulsion or foul or exhaust gases; and

l) To provide for the accomplishment of all these and other things in aunified and co-ordinated system of such nature as to allow flexibilityof utilization 0'5 energy.

Many other objectsand corresponding ac com lishnients will be apparentfrom a consideration of the following detailed description. The systemabout to be described utilizes that system of propulsion now commonlyknown as electric-the system in which the final propulsion motorsaredriven directly from generators operated by prime movers, without anyintervening electric storage. In

adapting this electric drive to a submarine,

and particularly for purposes of increased r'lesibility in operation,and for eflicient use of the limited interior space, I divide theengine-generator sets into several sets of different sizes, any or allof which may be used for driving the propulsion'motors.

Such division leads both to eilicieny and flexibility of operation. Forinstance it enables very slow speed propulsion of a sub marine withoutthe usual very low engine eiiiciency. It also makes for betterpropelling efliciency as the propellers are designed for operation onlyby the propulsion motors, insteadot being designed as a compromise foreiiiciency between operation by propulsion engines and propulsionmotors. And at the same time, this division of the power plant intounits of difierent sizes'enables the units to be located with highspace-using efficiency in the tapering hull of the boat.

In thus utilizing combustion engines on clusively for propulsion power,the present system provides for eficient air storage and for eilicientuse of the stored air and also of its en rgy oi compression; and alsofor efiicient use of the heat of combustion which otherwise would go towaste from combustion engines. The air is initially compressed tostorage by compressor units driven by the combustion engines. On comingout of storage the air is reduced in pressure by stages and is heated byheat exchange with sea water or heat exchange with the engines, at eachstage of expansion. The maximum being the preferred type marine system.

To utilize the energy of compression of the air, I prefer to provide anair pressure motor such 'as an air pressure turbine which drives anelectric generator which in turn delivers its output into the commonelectrical system which feeds not only the 'final propulsion motors butalso all other electrically operated appurtenances of the boat, such,for instance, as the lighting system and the small pumps necessary forventilation when the submarine is at rest. Thus, by making sucharrangement for utilizing the energy of compression, that energy isutilized under any and all circumstances of the submarine. v With thisgeneral idea of the system in mind, the invention as a whole, and manyother objects and accomplishments, will be best understood from thefollowing detailed description wherein I set forth, in more or lessspecific details, the preferred and illustrative form of the invention,reference for this purpose'being had to the accompanying drawings,-inwhich:

Fig. 1-1a is a more or less diagrammatic plan of asubmarine equippedwith my system; the complete figure being divided into two parts forconvenience of illustration;

Fig. 22a is a similar section elevation; 1 Fi 3 is a diagramillustrating the interrelations and interconnections of the variouselements in my system; In this diagram piping interconnections are shownin heavy lines and electrical interconnections in light lines; and

Figs. 4 and'5 are vertical sections of a typical Diesel engine unit asmay be used mmy system. 1

" 'As the description proceeds it will be noted at various points and asregards various fea-.

tures of the described system, that the invention isnot necessarilylimited to the particulars described. It may, however, be noted at theoutset that the system is not at all necessarily limited to the use ofDiesel engines,

except in some particulars wherein the system is especially adapted toDiesel engine op eration. On the' other hand, broadly speaking, any typeof combustion prime mover may be utilized.

In the drawings a typical hull is indicated at 10 and a typicalsuper-structure at 11. The

hull is divided into several various compar 'r ments and, in general,will containall those compartments, tanks, etc., usual or desirable tothe propellers, or, if the propellers be ar- I ranged forwardly inthehull, then the motors will in that case be arranged in the forwardpart of the hull close to the propellers.

In the stern portion of the hull I place the several engine generatorunits, each of which comprises a Diesel. engine 15 and a generator 16.In the present instance, I have shown three such units at each side,with the larger units of each set forward and the small units aft; so asto utilize to fullest advantage the space within the tapering hull. Justforward of the engine units are shown two compressor units 17 each ofwhich may be of any suitable number of stages; and each driven by amotor 18. Alongside these compressor units the air expansion flasks orreservoirs 19, 20, 21, may be situated. These are shown as three innumber as I show the air as being expanded in three stages. Of courseany suitable number of stages may be "used for air expansion; I merelyindicated here three as being typicaland suitable;

The propulsion motors, engine generator setsand compressorunits, so fardescribed, as well as the air'expansion flasks, are arranged induplicate sets for purpose of symmetry and utilization of space. But anexplanation of operation of a single set suffices for both, and so onlyva single set is shown in the diagram of Figure 3. To combine the twooppositely arranged sets of expansionflasks into a single'operatingfunit, the two flasks 19 may at 30 in Figures 2 and 2a; andthey are shown.

as interconnected in groups or banks, each bank being connected by apipe 31, controlled by valve 32, with the high pressure air line 33.This high pressure air line has a branch 33a leading to the highpressure outlet of compressor 17 a-nd'is controlled by a valve 34.Through this connection air may be compressed at suitable high pressure(say 3000'or more pounds per square inch) into the flasks. The comressor unitstakethe air for this purpose from the interior atmosphere ofthe submarine, the valve controlled inlet of the compressor being shownat 35 in Figures 2 and 3.

I It will be noted that the high pressure air line 33 is. so connectedto the several.

banks of air flasks that any one or more of the banks may be put intocommunication pressingair into the flasks. or for releasing air from anyselected set of flasks. Paralleling the high pressure air line 33 isa'high pressure exhaust gas line 36; and a valve controlled connectionismade at 37 between this high pressure exhaust gas line .36. and eachof the connections 31 to the severalibanks of flasks; and thereby thishigh pressureexhaust gas line may be put into communication with anyselected one or more of .the banks of flasks. This high pressure exhaustgas line, controlled by a valve 36a connects into the highpressure airline extension 33a; so-that, by proper manipulation of the high pressureair control valve 34 and the high pressure exhaust control valve 36a,compressor ,17 maybe connected so'as to compress air or exhaust gas intoeither the high pressure air line 33 or the high pressure exhaust line36. The high pressure exhaust line 36 has a branch 36?). controlled by avalve .360, leading overboard. And the inlet of compressor 17 not onlycomprises the atmospheric valve but also a connection pipe 40,controlled by valve 40a, and which communicates with the exhaust tank 41for the purpose of taking up the condensed residue of exhaust gases whenit is desired to compress them into any of the air flasks.

Paralleling the high pressure air line 33 is a first reduction airline42, which line is in communication with high pressure line 33through communications which include reducing valves 43 and shut-offvalves 44; There may be one such reducing valve communication from thehigh pressure to the first reduction line for each bank of air flasks.The reducing valves will reduce the pressure typically from the highpressure to a first stage pressure of say 800 pounds'per square inch.

.The first stage air line 42 has branches 452a and 4%, controlled byvalves 420, leading to an outboard coil 45 in which the expanded air isheated by heatexchange with sea water. theoutboard coil. being locatedexterior of the hull and within the super-structure. A valve 46 islocated in the. air linesiQ and between the branches 42a and 426 sothat, byproper manipulation of the valve 4:6 and the valves 4:20, airmay be passed through the outboard coil, or not, as desired.

After passing; the outboard coil 45, the first stage air line extendson, as at 42d and has a connection at 4:26 with the first reduction tank19 which acts as a reservoir for the first stage air.v Then this firststage air line 42' also has a connection 42f, controlled by'the valve43, to a. reducing valve i9. From the reducing valve a connection 50leads to an outboard heating coil 51, and from this coil 51 a connection52 leads to the second stage tank 20.

From the connection 52 a valve controlled branch 53 leads to thereducing valve 54 which has connection at 55 with the third outboardheating coil 56 ;;and from this third coil a. connection 57 leads to thethird stage air tank 21. i

The pressure in the second stage tank 20 may typically be 200 pounds persquare inch and the pressure in the third stage tank 21 may. betypically about 5 pounds per square inch. The air in-each of thesethreestage tanks and their interconnected pipe systems will have been atleast to some extent warmed by heat exchange with sea water; so that theenergy of compression at each stage is kept as high as possible orpracticable.

As I haveindicated before, the several stages of expansion maypreferably be selected so as to suit the operationof a Diesel engine,and to do away with the necessity of having special compressor units onthe engine. adapted to and is described with a 2 cycle engine, it willbe appreciated that it may be adapted, by making minor changes, to a 4cycle engine, as well as any type ofcombustion engine, and still bewithin the spirit of my invention. 7

For instance in Figures and 5 I show a unit of a Diesel engine whereinthe cylinder is shown at 60, the piston at 61, the injector valve at 62,the starting valve at 63, the scavenge valves at 64 and the exhaustat65. The injection air manifold is indicated at 66, the starting airmanifold at 67, the scavenge air manifold at 68 and the exhaust manifold at 69; and the piping connections are correspondingly indicated inthe diagram of Figure 3. The fuel injection air will be operated at thefirst stage pressure of say 800 pounds; and so a branch line 70leadsfrom the first stage line at 426 to feed air at that pressure tothe injector system of the several engine cylinders. Air at this samepressure is used for starting operations, and so branch connections areindicated in the diagram of Figure 3 at 71 to communicate air from thefuel injection air line 70. p

Air from the third stage at approximately pounds pressure is used tofeed the en- Though this system is particularly 4 5. gine scavenge. Forthis purpose the'air is led from the pipe line 57 through pipe 75 andthen through a heat exchanger. 76 through which the exhaust from theseveral engines is passed by exhaust communicating pipes 77 as indicatedin Fig. 2. And the low pressure air, leaving the heat exchanger via line78 communicates withthe scavenge air manifolds 68 of each engine. Alsoin communication with this low pressure airline 78 at 786; is a line 79which leads to reducing valves 80 to discharge air into the interior ofthe hull to keep upthe proper atmospheric pressure there. V

The exhaust gases, after leaving the heat exchanger 76 by way of pipe85, first pass through the outboard cooling coil 86 which 7 acts as anexhaust condenser to cool and condense the exhaust gases as far as ispracticable'bycooling with sea water. As a result of this condensation aconsiderable amount of liquid (mostly water) is produced, and

' volume.

tank may contain water or any other liquid,

or any chemical which by reaction with the exhaust gases tends tocondense or li uefy them. :The accumulated liquid in the ex aust tankmay be pumped'out by the bilgepump 91-operated by a motor 92, a pipingconnection from the tank to the pump being shown at 93, and a lineleading overboard from the pump at 94. I i. I 7 Under ordinary runningconditions the exhaust gas residue is taken from the exhaust tankilthrough theline 40 to compressor 17, and is forced out at therequisite high ressure from the compressor through tie iiigh pressureexhaust line 36 through exhaust line 36b overboard. If at any time it isdesired notto pass any exhaust gases overboard, for, purposes ofconcealment, the

' valves 36a in exhaust line36b may be close-d and the exhaust thencompressed into the high pressure exhaust line 36 and, by proper manipulation of the valves 37 compressed at high pressure into anyselected bank or banks of the air flasks/which at that time do notcontain air. Itwill be readily understood that, in order to provide forstorageof ex-' haust at any time during the submarine operation, atleast one bank of the air flasks mustbe at all times empty of the. airand ready to take the exhaust. To take additional exhaust storage whilerunning submerged,

. otherbanks of air flasks will be emptied of their contained airfastenough to be ready to take exhaust storage as banks are filled upwith exhaust. I VI I 'When the wide range of. ratesat which thecompressor- 17 will handle exhaust gases is considered, theimportance ofbeing able to operate the compressor over a wide range of speedindependently of the engine speed becomes apparent, especially since themaxi mum speed requiredv will undoubtedly be greaterthan the speed atwhich fresh air is compressed and this variable speed of compressoroperation not only has reference to compressing exhaust, but also toforcing it directly overboardas elsewhere explained.

In suchecase exhaust condensation may be partially or wholly disregardedand the com-- storage in the flasks.

When is subsequently desired torelease V the stored exhaust gases, thatcan readily, be done by simply connecting the -proper air flask bankswith the high pressure exhaust line 36, and connecting that line withthe exhaust line 36b, when the exhaust will be, expelled overboard underthe pressure of residue ,ofexhaust left in the flasks at the low finalpressure may be cleaned outby subsequently pumping air into the flasksand then discharging. The flasks are thuscleaned for subsequentreception of their compressed air charge.

The relatively small Interior ventilation of the submarine is, of

course, effected by the compressor 17 when air is being compressedintothe air flasks; because the compressor takes' its air from the submarineinterior. The compressor, how

ever, is, only operated to compress air when I i the vessel is on thesurface and atmospheric air is entering. It 1s, however, used tocompress exhaust, at least at certain times, when the boat is submerged;and during those periods the compressor 17 may beused for drawing foulair from the interior'and compressing it along with the exhaust gases bysomewhat opening ,the air intake 35 of the; compressor sothataiproportion of air from the interior will be taken in for compressionalong with the exhaust from tank 41. This is true also whenever thecompressor 17 is compressing exhaust gases overboard. So that, wheneverthe vessel is; running sub merged, and the exhaust gases are beingcompressed either into the flasks or overboard, the compressor 17' maybe used to draw ofi interior air and thus cause ventilation.

' At times when the vessel is atrest submerged, and the engines are notbeing operated and it is thus not desirable tooperate the air compressororcompressors 17, ventilation may be effected by a smaller compressor100 operated by a motorlOl. This compressor has its intake from thesubmarine interior and compresses through a high pressure line 102,controlled :by valve 103'to the high pressure airline 33,,andgthus tothe flasks. Seeing that compressor17 and compressorlOO need not at anytime be operated simultaneously, the high pressure air hue and itsdistributionsystem to the flask banks may thus be utilized to compressand store the foul air from the compressor 100 in any selected bank orbanks, to be subsequently released just as exhaust may be released. or,if so desired, this compressed foul air may be subsequently releasedback through the high pressure air line and through the reductionsystems, to be used, along with other air, in the engines and thus gointo the engine exhaust which is ultimately stored or pumped overboard.The thorough ventilation of the iio submarine interior is thus provided.at all times.

high pressure line '33 by pipe 151 controlled by valve 152. In averageDiesel engine operationthe oxygen content of the air is not completelyconsumed; and re-use of such once used air, either mixed with other airor oxygen, makes it possible in emergencies to maintain engine operationlonger than can be otherwise.

In order to utilize the expansion energy of the stored air or otherpressure stored gases, I may employ a turbine which may preferablycomprise three steps 105a, 1057) and 1050 (as many steps as there are inreduction ofair pressure), and this turbine may conveniently drive agenerator 106 which is connected into the general electrical system ofthe submarine. It is preferred to utilize a turbine of multiple stagesin order that as nearly as'possible the full expansive energy of the airor gases may be utilized. Thus the first turbine stage 105a may beconnected by a line 107 to the high pressure air line 33, and itsexhaust may go by line 108 to the first stage air line 42. Similarly thesecond-turbine stage 1055 will be connected by lines 109 and 110 betweenthe first stage air line 12 (through the lines 22) and the second stageconnection 50; and the third turbine stage 1050 be connected by lines111 and 112 between the second stage air line 52 and the third stageconnection 55.

Suitable valvular arrangements are included whereby the air in itsseveral stages of expansion may be passed in any proportion desiredeither through the turbine stages or through the several stage reducingvalves; and in each'case the exhaust connections of the turbine stagesare made so that the expanded exhaust gases will pass through theseveral outboard heater coils 45, 51 and 56;

so that, so far as the expansion of the air is concerned, the turbinestages perform exactly the same functions as are performed by thepressure reducing valves.

The turbine operated generator 106 has its output line connected intothe main electrical system so that this generator output may be flexiblyutilized for any power purpose. For instance, in the diagram of Figure 3theswitchboardrepresented at 121 takes the output of all the generators16, through their output lines 122, 123 and 12 i, and the output ofgenerator 106 through its output line 120; and from this switchboard runthe feed lines 125 to propulsion motor 13, and 126 to compressor motor18. Also from the switchboard a small storage battery 127 may be fed;and another switchboard 128 is illus- I trated as being fed from thestorage battery lines, which last mentioned switchboard controls thesmaller electrically operated elements and those which may want to beoperated at times when none of the generators are necessarily inoperation. This, for instance, includes the lighting circuits 129, thecompressor motor 101 which is fed by line 130, the spray pump motor 89which is fed by line 131 and the bilge pump motor 92 which is fed byline 1.32. The storage battery for these purposes need not be'verylarge-in fact it maybe quite small as compared with i the storagebattery size necessary for storage battery propulsion of a submarine.

When the submarine is being propelled, one or more of the prime moverengines is, of course,-being operated, with the propulsion motorsdirectly energized from the generator or generators then in operation.For normal propulsion on the surface the engines simply exhaustoverboard, either by operation of compressor 17 to raise the lowpressure required for that purpose, or by direct exhaust overboard. Fordirect exhaust overboard a valve controlled branch 135 may'lead fromexhaust line 87. Accordingly, while running on the surface none of theauxiliary machinery need be operated unless it is desired to charge theair flasks, when compressor 17 will be operated.

Normally all of the air flasks will be preferably kept charged with airin readiness for submergence, excepting a single bank of flasks. If theboat is submerged and there is no immediate necessity for concealment,the engine exhaust-is simply forced overboard by operation ofcompressors 17.

Air

from the flasks is released for interior ventilation and for engineoperation; and foul air from the interior may be removed also bycompressors 17 as long as the propulsion engines are operated.

Then if it becomes necessary to conceal the exhaust, that may becompressed at high pressure into any empty flask bank and, as has beenbefore indicated, such storage of exhaust may continue as long as thevessel is capable l? of running submerged, because there are always airflasks available for exhaust storage as they are emptied of their aircharge for engine operation.

In case the vessel is at rest submerged, then propelled in submergence,the turbine operated generator 106 adds a considerable amount ofelectrical energy forpropulsion purposes, or for compression of exhaust,or

for any of the various other purposes for I which power is required.Such utilization of the pressure energy is thus very flexible and is notconfinedto any one particular purpose. For instance, although thus thecompression energy may be utilized for exhaust compression, it is notnecessarily utilized for that purpose but may be utilized for propulsionor for any other power purpose. And one particularly advantageous resultflowing from this flexibility of poweruse is in this; that even whenthesubma-rine is at rest submerged, and only a small amount of storedair is being released for ventilation, the

corresponding small amount of energy, utilized through turbine 105 andgenerator 103 will be suflicient to supply a large proportion of thepower required by compression motor 101 even if the foul air is beingstored in flasks at high pressure. By compressing the foul airoverboard, or by storing it in the flasks at something less than thehigh pressure of original air storage, the turbine generator set 105,106 may be made to supply substantially all the power necessary forlighting'and small power purposes and for the compressor motor 101; sothat in such mannerthe submarine may lie concealed as long as its storedair will suflice for ventilation.

a I claim:

1. In a submarine, the combinatlon of a hull and a propeller therefor, apropulsion power plant including a combustion engine, air storage units,a compressor, intake means for the compressor whereby it may take eitherair or engine exhaust for compression, and a piping system connectingwith the air storage units and whereby the compressor may compresseither air or exhaust into any selected storage unit. I

2. In a submarine, the combination of a hull and a propeller therefor, apropulsion power plant including a combustion engine,

I air storage units, a compressor, intake means for the compressorwhereby it may take either air or engine exhaust for compression, and apiping system connecting'with the air storage units and whereby storedair may be released from any selected storage unit for feeding thecombustion engine.

3. In a.submarine, the combination of a hull and a propeller therefor, apropulsion plant including a combustion engine, a compressor adapted totake either air or engine exhaust for compression, air storage units, apiping system selectively connectible with any of the air storage unitsand with the compressor, an air discharge piping system leading from theselectivepiping system to the combustion engine and-to thehull-interior, and a second compressor adapted to compress airffrom thehull interior'into the selective piping system and thereby into anyselected storage unit.

plant including a combustion engine, means for cooling and condensingthe exhaust from said engine, and means for compressing and storing saidexhaust under pressure. 7

5. In a submarine, the combination of a hull and a propeller therefor, apropulsion plant including a combustion engine, means for cooling andcondensing the exhaust from the said engine, a compressor having intakearrangements to take either air or the condensed exhaust forcompression, air storage units, a selective piping system capable ofbeing selectively connected with any of the air storage units and withthe compressor, whereby either air or condensed exhaust may becompressed or stored in an selected storage unit, and means for fee ingair to the combustion engine fromthe selective piping system. I

6. In a submarine, the combination of a hull and a propeller therefor, apropulsion plant including a combustion engine, means for cooling andcondensin the engine exhaust by heat exchange wit 1 sea water, and meansfor compressing and storing the conplantincluding a combustion engine,means for cooling and condensing the engine exhaust by heat exchangewith sea water, a compressor, a plurality of air storage units, aselective piping system selectively connectible with any of the storageunits and with the compressor, whereby condensed exhaust may bestoredunder pressure in any selected storage unit, and means for feedingair from the selective piping system to the combustion engine.

8. In a submarine, the combination of 'a hull and a propeller. therefor,apropulsion plant including a combustion engine, a compressor energizedfrom the combustion engine and having an intake adapted selectively totake either airfrom the hull interior or the engine exhaust, pressurestorage means, and means connecting the compression side of saidcompressoreither to. the exterior of the submarine or topressure'storage means.

9. Ina submarine, the combination of. a

hull and a propeller therefor, a propulsion plant including a combustionengine, a compressor energized from the combustion engine and having anintake adapted selectively to take either air from 'thehull interior orthe engine exhaust, pressure storage means,

the second compressor energized from the combustion engine and havingits intake from the hull interior, and means whereby the compressionside of both said compressors 4. In a submarine, the combination of ahull, anda propeller therefor, a propulsion may be selectively directedoverboard or to the pressure storage means.

10. In a submarine, the combination of a hull and a propeller therefor,a propulsion plant including a Diesel type internal com bustion engineutilizing air at tWo difi'erent pressures for its operation, air storagemeans, a compressor energized from the engine and adapted to compressair into the storage means, and means for discharging air from thestorage at reduced pressures and feeding the air at such reducedpressures to the engine.

11. In a submarine, the combination of a hull and a propeller therefor,a propulsion plant including a Diesel type internal combustion engineutilizing air at two different pressures, a plurality of air storageunits, a selective piping system selectively connectible with thestorage units, a compressor adapted selectively to take air or engineex- I haust and compress into the selective piping system, and means fordischarging air and exhaust from the piping system at reduced pressuresand feeding the air at such reduced pressures to the engine.

12. In a submarine, the combination of a hull and a propeller therefor,a propulsion plant including 21. Diesel type internal combustion engineutilizing air at two different pressures, a plurality of air storageunits, a selective piping system selectively connectible With thestorage units, a compressor adapted selectively to take air or engineexhaust and compress into the selective piping system, and means fordischarging air and exhaust from the piping system at reduced pressuresand feeding the air at such reduced pressures to the engine, and oxygenstorage selectively connectible With the selective piping system.

In Witness that I claim the foregoing I have hereunto subscribed my namethis 17th day of February 1930.

ABNER R. NEFF.

